What does your water have in it that you want to remove? Can you get a local water report? My water here in the central part of the US is so loaded up with chlorine and chloramines that I dilute with RO water to at least 50/50...than add 1/4 teaspoon K metabisulfite [Campden tablet would work]. The Campden neutralizes the chlorine, etc immediately. We can get cheap RO water at the grocery store or WalMart so that's what I use. Also, the pH of local tap water is about 9.0 because of chems that are added to protect the pipes. I used to filter at home but it took quite a while for 10 gallons of brew water...Campden is immediate.
BTW I'm heading for Chipping Campden day after tomorrow [vacation] and found out Campden tablets were developed there a long time ago. So that's how they got their name.
Bill Frazier
Olathe, Kansas USA
near Kansas City